1. Field of the Invention
The present invention relates, in general, to an atmospheric pressure plasma generating apparatus using an induction electrode (IE), and more particularly, to an atmospheric pressure plasma generating apparatus using an induction electrode, having a structure in which one or more upper metal electrodes are disposed on the upper side and the induction electrode is disposed opposite to the upper metal electrodes in order to induce generation of a plasma, excessively accumulate charges on an induction electrode antenna, easily induce a plasma discharge at low voltage by utilizing a next discharge, and enable generation of a high density plasma, wherein a plasma is generated by an upper electrode and the length of the generated plasma is induced to increase downwardly by means of a lower electrode, so that an metal induction electrode and a dielectric material can be properly used and the length of the generated plasma can be increased through the lower electrode, enabling an efficient processing of a large area sample.
2. Background of the Related Art
In general, a plasma has a fourth material state, and consists of ion and electrons, which are generated by an externally applied electric field, etc., radicals, neutral particles and so on. The plasma has a material state of electrical neutrality from a comprehensive point of view. Ion, electrons, radicals, etc. within the plasma have been widely used for such fields as surface reforming, etching, coating, sterilization, disinfection, ozone generation, dyeing, purification of waste water and tap water, air purification and high luminance lamps.
The plasma can be classified into a low-pressure plasma (several mmTorr to several Torr) and an atmospheric pressure plasma (several Torr to 760 Torr) depending on generated pressure.
Of them, the low-pressure plasma can be easily generated, but requires expensive apparatuses for maintaining a low-pressure state, such as a vacuum chamber and an exhaust device. Further, the low-pressure plasma has a limit to mass-production processing due to the product input method of a batch type. In contrast, the atmospheric pressure plasma can be generated in the state of an atmospheric pressure (760 Torr), and thus does not require an expensive vacuum system. Further, the atmospheric pressure plasma is advantageous in that it enables a consecutive process and mass production.
The most widely used method as a method of generating a plasma while prohibiting arc discharge at an atmospheric pressure is a dielectric material barrier type (T. Yokoyama, M. Kogoma, T. Moriwaki, and S. Okazaki, J. Phys. D: Appl. Phys. V23, p 1125 (1990)), (John R. Roth, Peter P. Tsai, Chaoyu Lin, Mouuir Laroussi, Paul D. Spence, “Steady-state, Glow discharge plasma”, U.S. Pat. No. 5,387,842 (Feb. 7, 1995), “One Atmosphere, Uniform Glow discharge plasma”, U.S. Pat. No. 5,414,324 (May 9, 1995)).
Furthermore, an AC barrier type is a method in which a ceramic dielectric material for prohibiting arc discharge, such as alumina, is coated on both sides or one side of upper and lower electrodes disposed with an adequate gap therebetween, and high AC pulse voltage is applied to generate an atmospheric plasma.
The dielectric material barrier type of the upper and lower electrodes is not appropriate for a processing, such as a sample of a 3D structure, because the length of generated plasma is not large due to a limited distance between the electrodes. Plasma torch, plasma shower and so on are suitable for processing a sample of a 3D structure, etc., but are mostly used for arc plasma. Thus, plasma torch, plasma shower and so on are difficult in large area processing due to a small plasma generation area, and find limited fields due to thermal plasma. The plasma shower type (Y. Sawada, K. Nakamura, H. Kitamura, Y. Inoue, “Plasma treatment apparatus and plasma treatment method performed by use of the same apparatus”, U.S. Pat. No. 6,424,091 (Jul. 23, 2002)) using the dielectric material barrier employs corner or glow discharge not high temperature plasma of arc, and is a low temperature plasma shower type enabling a large area.
However, the plasma shower type using the dielectric material barrier is problematic in processing a sample of a 3D structure since the length of plasma generated is several mm.